Nice guide, I was using a similar method and this video helped me refine my route.
HOWEVER, I just fulfilled all the requirements and the achievement didn't pop. Anyone have a solution or similar experience. I'm gonna paste here what I commented over at TA:
I had it glitch on me solo/easy (local) also. Bought quick revive  & speed cola , went down, revived, bought who's who , other building and bought mule kick , jug , double tap  and finally pack-a-punched the ak74u from the wall . I also built the trample steam in the early rounds to watch my back, if that means anything.
Locations (if those matter) were:
 Quick Revive - normal place
 Speed Cola - Other elevator that goes to top floor of spawn tower
 Who's Who - Last elevator in spawn tower, tops out at PDW floor
 Mule Kick - Power Room elevator, right hand shaft
 Juggernog - Power tower shaft that doesn't go all the way to the top
 Double Tap - Power Room elevator, left hand shaft
 PaP - Power tower final shaft, only goes to roof and floor just below
I'm going to give it another go on a solo custom game, instead of choosing "Local" from the main zombies menu.
UPDATE: Just got it in a Solo custom game on Easy (set privacy to invite only). Used the same strategy as before, PaP'd my starting M1911 to Mustang & Sally since I was able to do this by Round 8 with a beastly 2x streak training zombies in the bottom of the upside-down tower after getting my spawn tower perks and before getting jug/mule/double/PaP. So the main differences were Public (custom/invite-only) instead of Local (still on easy), and I PaP'd my starting pistol, and the PaP was not the final perk (double tap was last, in that 2-floor only elevator that paints you into a corner).
Good luck guys!
PS The final thing I did differently on my successful attempt was to not pick up any parts whatsoever. On my first attempt I had built the trample steam, but on my successful attempt I didn't pick up any keys or building pieces.
Last edited by spxyu02; 02-05-2013 at 03:23 AM.